It is common in the art relating to internal combustion engines to drive a cam or camshaft through suitable means such as gear, chain or belt drives from the engine output means, or crankshaft, with a fixed speed ratio and phase relation between the driven camshaft and the driving crankshaft. However, numerous variable timing drive arrangements have also been proposed wherein the phase angle between the camshaft and the crankshaft may be varied manually or automatically during engine operation. In this way, variable timing of the engine valves may be provided.
Among various arrangements that have been previously proposed are the spring driven mechanical mechanisms of U.S. Pat. Nos. 3,262,435 Cribbs and 4,177,773 Cribbs and the hydraulic fluid actuated mechanism of 4,091,776 Clemens et al.